Large Language Models Enable Effective Deanonymization of Pseudonymous Online Users
By
mellosouls
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Summary
Researchers demonstrate that large language models can effectively perform large-scale deanonymization attacks, re-identifying pseudonymous users across platforms like Hacker News, LinkedIn, and Reddit with high precision. The LLM-based approach extracts identity-relevant features from unstructured text, uses semantic embeddings to find candidate matches, and reasons over top candidates to verify matches. In evaluations, LLM methods achieved up to 68% recall at 90% precision, substantially outperforming classical baselines, showing that practical obscurity for online pseudonymity no longer holds and privacy threat models need reconsideration.
Key quotes
· 4 pulledWith full Internet access, our agent can re-identify Hacker News users and Anthropic Interviewer participants at high precision, given pseudonymous online profiles and conversations alone, matching what would take hours for a dedicated human investigator.
Compared to classical deanonymization work (e.g., on the Netflix prize) that required structured data, our approach works directly on raw user content across arbitrary platforms.
In each setting, LLM-based methods substantially outperform classical baselines, achieving up to 68% recall at 90% precision compared to near 0% for the best non-LLM method.
Our results show that the practical obscurity protecting pseudonymous users online no longer holds and that threat models for online privacy need to be reconsidered.
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